In a liquid handling system used in chemical experiments and the like, liquid is transferred (dispensed) into and out of a liquid dispensing container (hereinafter, referred to as a “tank” in the description) using a tip for a pipet (hereinafter, simply referred to as a “tip” in the description) for subsequent tests.
When dispensing a relatively low volatile liquid (water, various salt solutions and the like) to a tank, an open-topped tank 50, shown in FIG. 14, has been used because the liquid will not lose in weight even if the tank is open.
On the contrary, when dispensing a relatively high volatile liquid (organic solvent, such as ethanol, methanol and acetonitrile) to a tank, the opening of the tank 50 is usually closed with a lid 52 because the liquid may lose in weight owing to its high volatile characteristics. And, when the liquid is dispensed into and out of the tank 50 using a tip 51, the lid 52 is detached from the tank 50.
However, in a case in which the tank 50, shown in FIG. 14, is used, the tank 50 cannot be tightly sealed even if this kind of lid 52 is used, and thus loss in weight of organic solvent owing to volatilization cannot be prevented. If the organic solvent in the tank 50 loses in weight, the initially transferred solvent may be reduced in amount. In a result, a problem of inaccuracy of quantitative analysis may be caused. Today, because of progress in microanalytical technique, volatilization of organic solvent will significantly affect a result of analysis. In addition, requiring to attach and detach the lid 52 every dispensing works leads to a problem in lowering operating efficiency of the dispensing operation and the subsequent tests.
Furthermore, as a tip 51 for a pipet, one made of resin having a higher chemical resistance than one made of metal has been in use. So, in view of sealing property of the tank, a septum, what is called, is proposed. However, the septum is only used for inserting a metal tip (needle) and therefore cannot resist several time of inserting and drawing of the tip. So, the septum is not applicable for practical use.
Consequently, to employ a tip made of resin, as shown in FIG. 15, a tank 50, the opening of which is covered with a sheet 53 having a single straight slit 54, is proposed. However, frequent inserting and drawing of the tip 51 and/or employing a plurality of tips 51 may cause significantly wear of the sheet 53 around the slit 54. As a result, the slit 54 remains opened and thus cannot be tightly closed. So, volatilization of the liquid and thus loss in weight of the liquid cannot be prevented.
To solve the problems, a tank 50 the opening of which is covered with a sheet 53 having a plurality of radial slit 55, as shown in FIG. 16, is proposed.
The radial slits 55 are formed corresponding to the tips 51. For example, when a series of eight tips 51 are used, the sheet 53 has eight of the radial slits 55.
However, when frequent inserting and drawing of the tip 51 increase, a friction between the slit 55 and the chip 51 deforms the radial pieces 55a and 55b of each slit 55. Consequently, sealing performance of the tank 50 still remains low.